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Rolex Bubbleback Projects --

R

RoXeW22

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Broke up my previous post so my open questions are here:​


What about using a Gen Bubbleback case?​

While I have found a few listings for spare gen Bubbleback cases, the issue is always wondering how to make an ETA movement fit. If I understand correctly, to build a Bubbleback franken with a gen case, I'd have to:
  1. Obtain the case and determine measurements
  2. Add an ETA movement and see how far off we are
  3. Translate those measurements into a movement holder that will need to be custom designed and 3D-printed (1 of 1)
Is that right? IF so...that sounds tempting, but also incredibly complex, especially when I have no experience figuring that stuff out.
I figured people built frankens in the past using gen bubbleback cases, but I have seen ZERO from scouring online :/



Where do I find these hands...​

I posted an image above of what the correct period hands should look like: Mercedes Hour Hand, Widening Minute Hand, and a Seconds Hand with a oval point on the other end. Based on my research online, the Hour Hand should be about 8mm, the Minute Hand about 11mm, and the Second Hand about 11-12mm. Furthermore, they should be blued steel, not gilt/gold.

BUT, after spending countless hours sifting through eBay, AliExpress, Esslinger, OFREI, StarTime and other watch supply websites -- there simply aren't any full sets (mixed or matched) that meet this criteria. The Minute Hand is really the most challenging -- Most minute hands are 12mm at a minimum, and the widening Minute Hand is quite hard to find, let alone one in blued steel. So, I have 3 options:
  1. Repurpose a set of hands I already have--I actually have a 36mm Japanese Bubbleback Homage, but unfortunately the Minute Hand is ~12mm (the hour hand works, and the seconds hand could be trimmed if needed)
  2. Spend $$$ to buy old-stock Bubbleback Hands and have them broached--According to caliber websites, the Bubbleback hands are (1.3mm x .75mm x 0.2mm) while ETA hands are (1.5mm x 0.9mm x 0.25mm) -- so I could buy a set for roughly ~$125-500, and have them broached -- but that would fix my length issue
  3. Spend $$$ to get someone to create custom hands--I believe there have been past builds where folks have created custom hands, right? So I'd have to try and figure out and design a custom set of hands, but again -- I'm unclear on price and colors



How do I source a dial blank to be used?​

Since I'm using an ETA 278X movement (see below), I'm going to need a new dial blank to provide to the dial maker that will fit this dial. Unfortunately, the ETA 28XX dial feet won't work with this movement. I already know I'll likely need a 25mm dial, but still at a loss as to how to source a dial blank. I have a HUNCH -- that if I took a 25mm ETA 28XX dial blank and just rotated it a bit, it would work...because as long as nothing is yet printed, it wouldn't cause an issue, right?

Here's a reference diagram I found showing the difference in dial feet between an ETA 27XX vs ETA 28XX -- any insights on how to use this to figure it out?

 
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R

RoXeW22

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OK, finally an update--one step forward, two steps back.

On the movement front ​

Things were looking promising -- at first. I found and bought a serviced ETA 278X dial that ran beautifully, was NOS from the 70s (prior to its service) and just needed to remove its date parts. I bought the same movement family because I figured it would fit best in the rep bubbleback case I had obtained. So then it was on to the dial...

On the dial and hands front ​

After looking into gen dials (either too expensive and/or redialed) and rep dials (none available), I decided the custom dial route made the best sense, but dialmaker Fizzz on Homage forums only uses ETA 2824 dial blanks. So the big question was: Could a ETA 2824 Dial Blank be shifted in orientation to fit an ETA 27XX movement?

Meanwhile I obtained a set of ETA hands that are in the exact style I was looking for and the correct lengths, so that was done.

Back to movements...​

After a fair amount of research and back-and-forth across various forums, no one could definitively provide me with technical specifications for dial feet on an ETA 27XX movement, nor could I find a suitable blank dial that would fit.

Therefore, even though I had bought a replacement ETA movement, I decided to shift directions and purchased a NOS Swatch Automatic from the 90s, and took out its ETA 2842 Movement instead (21,600 bph and roughly the same size as the ETA 27XX movements in diameter, but slightly thinner).

So that leaves the case...​

As mentioned earlier, I obtained a rep Bubbleback case (there's only one AFAIK), but upon comparing it to a gen bubbleback, I realized it wasn't close enough for my standards, so I decided to settle in and look for a gen bubbleback case. Most were ridiculously overpriced, but I finally managed to find a decent one, but with a poorly fitting caseback -- so now I need to find a replacement caseback.

So here's where I am after 2 months -- a case and a movement and hands :)



Requests and Questions​


  1. If anyone has a spare Bubbleback 2940 caseback -- I will gladly take it!
  2. Can anyone tell me where the dial feet holes are on this ETA 2842 movement? I'm can't find them, and can't fit my ETA 2824 blank dial in either. Image below. I know where they're supposed to be, but I don't necessarily see it on here. The photo below shows the movement at the correct orientation, but the one dial hole that I think I see is covered (see red arrow).

 
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Mkempes

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RDRoss

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Ok, I’m going to be speaking out of school so to speak, but you could always try a Tudor dial for the 27xx series and use it as the base for the dial. ALso, you might want to look at the baltany bubblebacks on Ali. You might be able to scavenge parts.

Just a couple of random thoughts.
 
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RDRoss said:
Ok, I’m going to be speaking out of school so to speak, but you could always try a Tudor dial for the 27xx series and use it as the base for the dial. ALso, you might want to look at the baltany bubblebacks on Ali. You might be able to scavenge parts.

Just a couple of random thoughts.
Click to expand...
Thanks @RDRoss -- all inputs welcome! I actually looked into Baltany when I got started, but their parts aren't really compatible with Gen because of the enlarged dimensions (their cases are 36mm vs the 31-32mm of the Gens) and different design details. Baltany would def be a great base for creating a "larger" bubbleback for sure.

As for the dial, I forgot to mention one part -- which is that Fizzzz' gilt process uses brand new dial blanks, and he doesn't have the ability to use an existing dial to make it blank again etc. -- the only option would be someone who can solder dial feet in a ETA 27XX configuration, THEN I send it to him.

Ultimately I have 3 options (and thanks @Mkempes for keeping me on the right track):
  1. Use the ETA 2842 movement, order the dial from Fizzzz, cut the dial feet, and use dots/tape
  2. Order a low beat ETA 28XX movement (any experience with Powermatic 80s?) and use the dial without cutting the feet
    1. I hear 2846s aren't that reliable though, so next best thing would be to take a Powermatic 80 and pull out the date parts and swap the set bridge so there's no ghost position
  3. Use an older ETA movement (my ETA 2782, or even more accurate, an ETA 2451 since that beats at the correct 18.8K bph) and still end up cutting the dial feet
Seems like cutting the dial feet would save me the headache of needing to source/pay for another movement, but I'm just not sure how good of solution it is...
 
RDRoss

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A couple of thoughts. Cut the dial feet, sand the dial and use replacement feet (easy to find for folks like Esslinger, Hortec brand). You can even use dial dots for the adhesive if you want or you can solder (not recommended) or even epoxy the buggers in place. It is a pretty painless task.
You also might want to consider looking at something like this (EBay listing) as a donor source and modifying the hands for the movement.

Either way, best of luck on the project. These are truly beautiful watches.
 
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